The present invention relates to an engine brake system of a two-cycle engine, and more particularly to a system for increasing an engine braking effect of the two-cycle engine.
The two-cycle engine inherently has low pumping loss compared to the four-cycle engine, because the two-stroke cycle of the two-cycle engine completes with one-revolution of a crankshaft. Consequently, a vehicle driven by the two-cycle engine has a small engine braking effect
Japanese Patent Application Laid-Open No. 61-272425 disclose a two-stroke engine having a system for increasing the braking effect of the two-cycle engine. The combustion chamber of the engine has a valve for communicating the chamber with the atmosphere through an exhaust pipe. When a grip for controlling a throttle valve of the engine is further rotated from an idling position to a more closing position, the valve is opened to communicate the combustion chamber with the atmosphere. Thus, gas in the chamber flows alternately passing through the valve in accordance with the reciprocation of a piston, generating resistance against the piston of the engine to increase the engine braking effect.
However, the gas in the combustion chamber is decompressed, causing deterioration in combustion.